The present invention relates to compositions for the manufacture of organo-mineral products, products obtained therefrom and their use.
Methods for the manufacture of porous (foamed) and non-porous organo-mineral products by the conversion of polyisocyanates and aqueous alkali silicate solutions (water glasses) are known, for example, from DE-A-177 03 84, DE-A-246 08 34 and EP-B-0 000 579. In these instances, alkali water-glasses with a different solid-substance content and different ratio of Me2O/SiO2 (Me: alkali metal) are preferably used.
Organo-mineral products characterized by a high mechanical strength are described in EP-B-0 167 002. Polyisocyanate in an aqueous alkaline solution containing SiO2 is induced into trimerization by the addition of a defined quantity of a polyisocyanate trimerization catalyst.
Initially, the NCO/water-glass reaction is largely suppressed, so that a quantity of gaseous CO2, controllable by the formulation, is produced, which is optimally used for the reaction with the water glass. During the reaction, two interwoven polymer structures are simultaneously formed, so that there is a dense high-strength network in the organo-mineral product produced.
In the first stage of the reaction, a proportion of the polyisocyanate reacts with the water to form polycarbamide, with the separation of gaseous CO2. The CO2 produced in situ reacts instantaneously with the Me2O component of the water-glass solution to form Me2CO3xc3x97H2O. By the bonding of the Me2O from the water-glass solution, the SiO2 component is induced to form polysilicic acid. Considerable quantities of heat are released in the reaction, so that, in the next stage, a particular further proportion of the polyisocyanate can take part in the trimerization reaction. Initially trimerized products for their part at least partly undergo further trimerization, so that a branched high-molecular structure can be formed.
A similar concept is applied in mining and tunnelling to stabilize coal and rock, as well as in the construction industry in general to stabilize and consolidate stone and brickwork, as in the preservation of old structures, for example, and is described in EP-B-0 167 003.
For application purposes, it is in most cases desirable in practice to process two-component systems, consisting of a water-glass component (component A) and an isocyanate component (component B), wherein the catalyst can be added either to component A or component B. On the one hand, the catalyst should be chemically compatible with the component concerned, and on the other there should be an even dispersion of the catalyst in the component.
In the isocyanate component, the stable dispersion/solution of a catalyst presents no problem, provided moisture is strictly excluded whilst working. Heterocyclically substituted ethers which can be stably dispersed in the isocyanate component are described in EP-B-0 636 154. In practice, however, this is only possible in closed systems, such as in spray cans or with cartridge methods.
The catalyst is therefore generally added to the water-glass component. Whereas, in the isocyanate component, stable dispersion of the catalyst presents no problem, provided the exclusion of moisture is ensured, in the water-glass component, on the other hand, it is impossible to prevent floating or hydrolysis of the catalyst in the highly alkaline solution, so that the catalyst can be added only shortly before the components are mixed, or must be carefully redispersed in the water-glass component shortly before being brought together with the other components.
It has been observed that the tendency towards dehomegenization can be reduced if antimony trioxide is added to the mixture (EP-B-0 167 002+003). Even this, of course, does not produce a dispersion which can be stored for months. Using the dispersing agents, solubilizers, stabilizers, emulsifiers, wetting agents, surfactants or polyols has not yielded a completely satisfactory result, either.
Catalysts used in the past have been amine catalysts common in polyurethane chemistry, such as tertiary amines, tertiary amino-alcohols or polyamines. Besides these, the trimerization catalysts known from EP-B-0 167 002 and EP-B-0 167 003 are also used: these are similarly tertiary amine catalysts or Mannich bases. Metallo-organic compounds, such as dibutyl tin laurate, are described in EP-B-0 016 262. With the tertiary amines and Mannich bases customarily used as catalysts in the past, even when polymers have been used on the isocyanate side, mechanically strong, but relatively brittle, hard products have in fact been obtained, in which the properties of the product are difficult to control.
The invention is consequently based on the problem of producing new organo-mineral products which exhibit the desired properties, are cheap and can be manufactured in a simplified manner.
This problem has been solved by the surprising discovery that primary amino-alcohols can be stably dissolved as catalysts in the water-glass components, at the same time resulting in organo-mineral products with the desired properties. This is surprising, insofar as primary amino-alcohols are hardly used in polyurethane chemistry, since undesirable effects, such as xe2x80x9cswellingxe2x80x9d of the reaction mixture, often occur as a result of the extremely high reaction rate. The controllability of the desired product-properties also decreases as the reaction rate increases. It is all the more surprising, because the use of primary amino-alcohols not only solves the long-standing problem of the stable dispersibility of the catalyst in the water-glass component, but also opens up the way to organo-mineral products with specific properties/characteristics. With the tertiary amines and Mannich bases which have customarily been used as catalysts in the past, even when polymers have been used on the isocyanate side, mechanically strong, but relatively brittle, hard products have in fact been obtained. With the existing invention, it has now become possible to produce organo-mineral products which are not only characterized by a high mechanical strength, but in addition also by outstanding elastic properties, whereby a high mechanical load carrying capacity is obtained.
The subject of the present invention is consequently a compositions comprising a component (A) containing an aqueous alkali silicate solution and a primary alcohol as a catalyst, and a component (B) containing a polyisocyanate.
The subject of the present invention is further an organo-mineral product, essentially from the conversion of polyisocyanates and aqueous alkali silicate solutions, in the presence of a primary amino-alcohol as a catalyst.
The subject of the present invention is also the use of an organo-mineral product as a building material, coating material, sealant or insulating material, or as a cement or adhesive.
The essential constituents of the reaction mixture for the manufacture of organo-mineral products are an aqueous water-glass solution, a polyisocyanate and a primary amino-alcohol as catalyst.
The catalysts according to the invention preferably exhibit the following general formula: 
in which R1 and R2, independently of each other, represent a hydrogen atom, a hydroxyl or methyl group, and m, n and p, independently of each other, have the value zero or a whole number from 1 to 20, preferably 1 to 10, and especially 1 to 4, with the condition that they cannot all be zero.
Catalysts in which n=1, 2 or 3, m=1 and pxe2x89xa70 are preferable used.
The aforementioned catalysts can be used individually or as a mixture.
In the composition of the water-glass solution which is customary and is preferably used according to the invention, the molar ratio of catalyst to NCO groups is 2 to 150, and preferably 8 to 40 mmol catalyst per mole of NCO. The molar ratio of the catalyst to SiO2 is preferably 5 to 100 mmol catalyst per mole of SiO2. The molar ratio of catalyst to Me2O is preferably 5 to 100 mmol catalyst per mole of Me2O.
Organo-mineral products with particularly favourable properties are obtained, for example, when polyisocyanate and water glass are used in such a quantity and composition that the above-mentioned ratio of quantity of catalyst to NCO groups is obtained, together with the similarly mentioned suitable ratio of NCO/SiO2. The quantity of CO2 generated should be absorbed by the proportion of Me2O as completely as possible.
The catalyst is preferably used in an absolute quantity of 0.1 to 5.0 g, related to 100 g of water-glass component A.
Furthermore, a co-catalyst can be added to the reaction mixture or to the individual components A and/or B. This can consist, for example, of a trivalent iron compound, such as FeCl3. Other inherently known co-catalysts can also be used, e.g. tri-alkylphosphanes, such as trimethylphospholine, alkali metal salts or carbonic acids, such as sodium acetate or sodium maleate, or transitional metal compounds, such as Sb2O3, ZrOCl2, SbCl5 or CuCl. Mannich bases in particular, such as 2,4,6-tris(dimethylaminomethyl)phenol, are suitable for use in the water-glass component. Morpholine ethers, such as dimorpholinodiethylether, in particular, are suitable for use in isocyanate components.
Components A and B are preferably mixed in a volumetric ratio of 3/1 to 1/3, especially 2/1 to 1/1.
The primary amino-alcohol catalysts according to the invention can be stably dispersed in the water-glass component. The non-separating-out of component A permits unrestricted usability and storability of the compound. Storage tests have shown that both component A and component B can still be processed after several months, without loss of quality. Time-consuming redispersal of the catalyst can consequently be dispensed with.
In previously known systems employing trimerization catalysts, transformation of the mixture begins with reaction of NCO groups with the water of the water-glass solution. Gaseous CO2 and polycarbamide are produced. This transformation takes place exothermally, and the heat liberated causes the start of trimerization of the remaining NCO groups under the action of the catalyst. The liberated CO2 for its part is transformed with the Me2O of the water glass into alkali metal carbonate. The Me2O component is taken from the water-glass, and, in the course of transformation, the remaining silicic acid component forms a three-dimensional inorganic structure, which combines with the organic polymerisate simultaneously produced to form a interwoven network of great strength.
Without specifying a particular theory, it is assumed that, in contrast to the above reaction-mechanism, in the transformation of the composition according to the invention the primary amino-function, as well as the terminal OH function(s) of the catalyst, enters into a reaction with the isocyanate component. Whether trimerization also takes place is unclear. The isocyanate component may also be present as a polymer. Depending on the functionality of the catalyst used, an even higher-molecular weight prepolymer is thereby formed, which encloses the polysilicic acid structure produced and reinforces the elastic properties of the finished product. The degree of cross-linking in the prepolymer, and consequently in the finished product, can be determined by the functionality of the amino alcohol used. Organo-mineral products can thereby be obtained, in which the elastic properties/characteristics can be tailor-made.
In the compositions in the present invention, the aqueous alkali silicate solutions customarily used in this field can be used in component A, for example the water-glass solution described in EP-B-0 000 579 and in DE-A-2 460 834. By virtue of their easy availability and low viscosity, sodium water-glasses are preferred.
Sodium water-glasses, with a relatively high solids-content, favourably in the range from around 30 to 60 percent by weight, and especially roughly 40 to 55 percent by weight of inorganic solids, are preferably used. In theory, even higher-concentration water-glass solutions can be used and be employed within the meaning of the invention. Because of the resultant processing speeds, such water-glass solutions have little practical significance.
The molar ratio of SiO2 to Me2O in the water-glass solution used is preferably comparatively high and is favourably in the range from around 2.09 to 3.44. A range from around 2.48 to 3.17, and especially 2.40 to 2.95, is particularly preferred. Formation of the three-dimensional silicic acid structure is favoured by an Me2O content within the range indicated above.
The polyisocyanates customarily used in this field can be used as component B in the compositions in the present invention, for example the compounds referred to in EP-B-0 000 579 and in DE-A-2 460 834. Also suitable are NCO pre-adducts, as known in the manufacture of polyurethanes and as described in DE-A-2 460 834.
Polyisocyanates which are easily able to assume a three-dimensional structure are preferred in the compositions in the present invention. These are compounds which, as far as possible, exhibit no steric hindrance to the NCO groups involved in the transformation. One special example of such a sterically unhindered polyisocyanate is 4,4xe2x80x2-diphenylmethanediisocyanate, which can also exist in the form of the phosphogenation product of aniline formaldehyde condensates (crude MDI). A reaction product of crude MDI with a diol, with an OH number of 28 to 1800, especially with an OH number from 40 to 100, and preferably with an OH number from 50 to 60, is suitable as a prepolymerisate. Ethylene glycol and, by virtue of its low reactivity, especially diols based on propylene glycol, for example, are suitable as diols.
The polyisocyanates used according to the invention preferably have an NCO-group content of roughly 10 to 55% by wt., referred to the mass of the polyisocyanate. Polyisocyanates with an NCO-group content of roughly 10 to 30% by wt. are particularly preferred. A smaller proportion of NCO groups in the polyisocyanate makes the formation of a three-dimensional organic structure difficult. On the other hand, with a higher NCO content, it is easy for too much gaseous CO2 to be liberated, which can result in overhardening of the inorganic part of the product and favours uncontrolled foaming.
Nucleating and stabilizing substances can also be added to the compositions in the invention. Suitable nucleating substances include, for example, finely divided solid substances, such as silicon dioxide or aluminium oxide, possibly together with zinc stearate, amorphous silicic acid or metasilicate. Of these, the silicon dioxide precipitated from the colloidal water-glass solution is preferred as a nucleating agent.
Silicons with a basis of polysiloxanes are suitable stabilizers. These can be added in a quantity of roughly 0.2 to 2, and especially 0.8 to 1.4 percent by weight, referred to the total mass of the reaction mixture.
Depending on the desired properties/characteristics of the organo-mineral products being manufactured, still further additives can be added to the compositions in the invention. These include, for example, organic compounds exhibiting residues capable of reacting in relation to isocyanate groups. Examples of these include polyols, such as polyester and polyether polyols and phosphonate esters known in polyurethane chemistry. The quantity of the polyols should be limited, so that their addition does not disturb the formation of a three-dimensional organic structure and of an inorganic structure interwoven with it. The addition of polyol or phosphonate ester is therefore expediently limited to a maximum of 2 to 45% by wt., preferably 10 to 20% by weight, referred to the isocyanate component.
In order to reduce the flammability of the organo-mineral products in the invention, flame-inhibiting substances can be added to the compounds or individual components. The flame-inhibiting or flame-retardant substances known in plastics chemistry, such as phosphates and borates, are suitable for the purpose. The quantity of flame-inhibiting substances can be in the range from 2 to 30% by wt., referred to the isocyanate component. Phosphonate esters, such as tri-xcex2-chlorethyl phosphonate or tri-xcex2-isopropyl phosphonate, for example, can be added as a flame protection agent and to reduce viscosity. Furthermore, liquid organic carbonates, phthalates or halogenated alkyl phosphates are suitable as stabilizers, emulsifiers or as viscosity reducing agents.
Furthermore, additives and fillers can be added to the compositions in the invention, to bring about further reinforcement of the organo-mineral products. Examples of suitable fillers include diatomaceous earth, aluminium oxide hydrate, magnesium silicate, asbestos powder, chalk, asbestos fibres and glass fibres. The quantity of filler added is governed primarily by the viscosity of the mixture. It is preferably in the range from 0.1 to 30% by wt., referred to the weight of the water-glass solution used.
If desired, pigments or dyes can be added to the components.
In order to reduce viscosity, an aqueous alkali hydroxide solution can be added to component A. An NaOH solution is suitable as the alkali hydroxide solution, for example, preferably in the form of a 30-50% solution, and especially as a 45% solution. Component A can further contain the flame-inhibiting additives, fillers and dyes. Component B, the polyisocyanate, possibly contains the co-catalyst, as well as the stabilizer and, where applicable, the additives and fillers compatible with the above-mentioned constituents.
To produce the organo-mineral products in the invention, components A and B are carefully mixed. The starting time of the mixtures obtained is generally between 5 seconds and 5 minutes, and can be controlled as required. Where appropriate, the components or mixture can be heated or cooled, in order to adapt the starting time to requirements.
In their curing behaviour, the compositions in the present invention are similar to polyurethanes. They offer a well-balanced curing performance as previously-known organo-mineral products and are also characterized by an increased early strength. Catalysts in the past have brought about continuous and spontaneous curing. The longer curing phase of the organo-mineral products in the invention permits more flexible processing, compared with the known products.
The compositions in the present invention are characterized by storability and the associated unrestricted usability. In particular, a stable dispersion of the catalyst in the water-glass component is ensured in the compositions according to the invention. The floating of the catalyst previously observed no longer occurs, so that it is possible to dispense with time-consuming redispersal of the catalyst prior to processing. The compositions in the invention thereby enjoy a constant quality of processing and can be stored without limitation.
In addition, the degree of cross-linking in the finished product can be controlled through the choice of catalyst functionality. Organo-mineral products can thereby be produced with tailor-made properties/characteristics in the finished product. In particular, the present products are characterized by high elasticity, combined with a high mechanical load-carrying capacity.
The organo-mineral products in the present invention are consequently versatile in use. The compounds produced can be applied, for example, by dipping, spraying, using a palette-knife, by injection, with a roller or by painting. They are therefore suitable for a wide range of applications, e.g. as building materials, coating materials, sealants and insulating materials, as well as cement or adhesive. In addition, they offer the advantages of cost-effective raw materials, exhibit a low flammability and have an anti-corrosive action. In addition, an increased solvent-resistance and low swelling-effect are provide by silicic acid component. The organo-mineral products of the invention are thus characterized by resistance to all common solvents, such as mineral oils or benzene, but also to lyes and acids.